Mapping the stability of the Greenland Ice Sheet

In the coming century, the Greenland Ice Sheet (GrIS) is expected to be one of the main contributors to global sea-level rise. In addition, it is thought to be a tipping element due to the existence of positive feedbacks governing its mass balance. Previous studies have explored its stability across a range of temperatures, from present-day conditions to a global warming of 4°C, showing a threshold behavior in its response. However, it is known this threshold has already been exceeded in the past. During the Holocene Thermal Maximum, when Greenland temperatures were 2–4°C warmer than today, the ice sheet retreated beyond its present-day margin but did not fully disappear. Ice losses depend on the level of warming, but also on the rate of forcing and how long the forcing remains above the threshold.  Therefore, we propose studying the stability of the ice sheet over a broader temperature range: from the Last Glacial Maximum to a warming of +4°C,  and examining its current state within the bifurcation diagram. For this purpose, we use the ice-sheet model Yelmo coupled with the regional moisture-energy balance model REMBO and a linear parameterization of the oceanic basal melting.